The present invention relates a towed acoustic source array of marine sources such as vibrator sources (Vibroseis type) of MULTIPULSE(trademark) sources, for example of the type described in U.S. Pat. Nos. 4,131,178 issued Dec. 26, 1978, U.S. Pat. No. 4,207,962 issued Jun. 17, 1980, and U.S. Pat. No. 4,362,214, issued Dec. 30, 1986. The invention is especially suitable for use as a towed geophysical array for underwater geophysical exploration applications.
The array may use geophysical sources such as air guns as well as hydraulically driven marine vibrator units and MULTIUPLSE(trademark) sources.
It is the principal feature of the invention to provide a towed array system where the depth and lateral position of each source may be set under tow and maintained and also where the separation of the sources may be varied so as to facilitate stowing thereof on a towing vessel and deployment to prescribed spacing between the sources.
Geophysical and other source arrays for marine applications have heretofore been proposed. See, for example, Bouyoucos, etal U.S. Pat. No. 5,841,733, issued Nov. 24, 1998. A towed source array system, particularly a geophysical source array for marine applications, which can readily be stowed aboard a vessel and then deployed at prescribed depths and with lateral positioning and maintained during operation at such depths and positioning has heretofore not been provided.
Briefly described, a marine towed array in accordance with the invention uses a plurality of tow bodies each containing an acoustic source. Each tow body including the source and any associated power supply and control systems are positively buoyant and contain control planes for driving the bodies under tow to a prescribed depth and lateral position and holding them there. Preferably the bodies are interconnected to the ship and to each other in series by electro-mechanical umbilical, tow cables. The bodies may contain reels from which the cables may be wound and unwound to change the spacing of the sources. The first tow body, at one end of the array, is attachable to the towing ship and the bodies, their positioning, their sources and reels are controllable from the ship.